Accelerator Neutrino Physics I: Present Decade CHRIS WALTER, DUKE UNIVERSITY TAUP 2013 September 12th 2013 September 2013: Where do we stand? Large Θ13! Can we measure CP viola6on? • The measurement of non-zero θ13 has changed the nature of discussions and presentaons about the current experiments. • I’ll go over some experimental issues related to the accelerator experiments and try to teach you how to compare the experimental results. • Emphasis on long-baseline: T2K, MINOS, OPERA • I’ll try to explore what can we expect to know before the next generaon of experiments starts. 09/12/13 Chris Walter - TAUP 2013 2 OSCILLATION EXPERIMENTS How do νs oscillate? “Flavor” states are mixture of mass states. ⇥ cos θ sin θ ⇥ ⌫µ = ⌫2 cos ✓ + ⌫3 sin ✓ µ = 2 ⌫ = ⌫ sin ✓ + ⌫ cos ✓ ⇥τ sin θ cos θ ⇥3 ⌧ − 2 3 ⇥ − ⇥ ⇥ ⌫ (t) = eiE2t ⌫ (0) cos ✓ + eiE3t ⌫ (0) sin ✓ | µ i | 2 i | 3 i 1.27∆m2L P = sin2 2θ sin2 µτ E Reactor+ Beam Atmos Oscillaons unknown Solar Oscillaons c23 = cos ✓23 s23 =sin✓23 09/12/13 Chris Walter - TAUP 2013 3 QuesGons to answer • What is the paern of neutrino masses? • Is there CP violaon in the neutrino sector? Is it big enough to drive lepto- genesis and is it related to the quark sector? “Normal” “Inverted” In a beam experiment, the signal for non-zero θ13 is νe appearance in a pure νµ beam. There are differences in the rate of appearance between neutrinos and anti-neutrinos if there is CP violation and also for the different hierarchies in matter. 09/12/13 Chris Walter - TAUP 2013 4 How do you build a long-baseline experiment? (1st example: K2K -> MINOS -> T2K -> Nova) GPS Satellite (broadcasts time) Proton Synchrotron Protons Neutrinos Pions Decay Pipe Magnetic Horns Near detectors Always the same pattern: Accelerator -> Target -> Horns -> Decay Pipe -> Near detector -> Far Detector 09/12/13 Chris Walter - TAUP 2013 5 On and Off-Axis Beams Super-Kamiokande Neutrino Source Off Axis (2.5°) off-axis Proton Beam ° on-axis Neutrino Beam π 2.5 monitor = Θ 0m 120m 280m 295 km 400 The kinema?cs of pion decay allow at 295 km 350 us to make a narrower neutrino Peak flux is higher beam. All 300 2º and energy band is narrower. 250 200 (GeV) ν E 150 High Energy 100 tail causes Backgrounds 50 0 0 1 2 3 4 5 Epion (GeV) En (GeV) 09/12/13 Chris Walter - TAUP 2013 6 Oscillation searches at accelerators There are two types of searches: Appearance and Disappearance • Appearance: MiniBoone, T2K, Nova, • Disapearance: MINOS, K2K, SK OPERA disappearance: νe appearance: νµ determine θ and Δm2 determine θ13 23 23 Enough energy to produce lepton in NOT enough energy to produce CC reaction. lepton in CC reaction. 09/12/13 Chris Walter - TAUP 2013 7 How do we measure θ13? 2 2 2 2 Δm23L P(νµ →νe ) = sin θ23 sin 2θ13 sin + sub-leading terms 4Eν (sinδ is in here) Schematic figure νe appearance is crucial for studying the MH and CPV! Measure the electron appearance probability on top of a background For appearance three main types of background: 0 intrinsic νe , misidentified π , mis-identified charged µ We need a very high intensity beam and a large target. Make a pure neutrino beam and look for electrons to appear. 09/12/13 Chris Walter - TAUP 2013 8 The T2K Experiment Super-K water Cherenkov Detector as far detector. Uses the JPARC accelerator complex 295 km away Far detector: Super-K On and off-axis hybrid near detectors ν eCC BG NC ‣ 50 Kton Water Cherenkov Detector ‣ >11,000 PMTs read out by QTCs ‣ Image processing for reconstruction 09/12/13 Chris Walter - TAUP 2013 9 T2K observaon of νe Appearance normal hierarchy Inverted hierarchy 4.6 events expected background 28 events observed 20.4 ± 0.8 events expected @ sin22θ = 0.1 7.5σ significance for non-zero θ13 First ever observation (>5σ) of an explicit ν appearance channel 09/12/13 Chris Walter - TAUP 2013 10 Let’s think about these regions! 09/12/13 Chris Walter - TAUP 2013 11 T2K νμ Results (Run I-III) Maximal mixing is not the same as maximum Shows the power of the off-axis technique! disappearance if θ13 is not zero! 205 +- 17 events expected (no oscillation) 2 2 2 sin 2θ23 Δm32 χ / ndf Nobs Nexp θ23 ≤ π/4 1.000 2.44e-3 56.04 / 71 57.97 58 θ23 ≥ π/4 0.999 2.44e-3 56.03 / 71 57.92 09/12/13 Chris Walter - TAUP 2013 12 T. Vahle (W&M) New MINOS Results Updated results: 735 km 10.7 x 1020 pot neutrino 3.4 x 1020 pot anti-neutrino Near 1 kton Far 5.4 kton 37.9 kton-years atmospheric Appearance: Disappearance Atmospheric Use stasGcal separaon based on a paern matching library Combine Beam and Atmospheric data: 09/12/13 Chris Walter - TAUP 2013 13 T. Vahle (W&M) PUTTING IT ALL TOGETHER ¢ Solar mixing parameters fixed ¢ θ13 fit as nuisance parameter, constrained by reactor results - TAUP 2013- 2 ¢ �CP , θ23, Δm unconstrained Vahle ¢ major systematic uncertainties included as nuisance parameters 14 T T. Vahle (W&M) MINOS CPδ Dependence Appearance Only Appearance+Disappearance 09/12/13 Chris Walter - TAUP 2013 15 Let’s compare experiments! 09/12/13 Chris Walter - TAUP 2013 16 T. Vahle (W&M) MINOS+ is coming…. Simulated ν Beam • MINOS will conGnue to run in 5.4 kton, 6 × 1020 POT the NOvA era 1000 • ME beam peaks above the MINOS+ oscillaon dip on axis NOvA • But they get a lot of events! MINOS – ~4000 muon neutrino CC 500 events per year expected at Preliminary FD CC Events / GeV µ • Unique test of oscillaon ν paradigm with sensiGvity to 0 0 5 10 15 20 exoGc signals Eν (GeV) 09/12/13 Chris Walter - TAUP 2013 17 D. Duchesneau (Annecy LAPP) OPERA tau appearance experiment Uses ECC (Emulsion Cloud Chamber) Electronic trackers point With automatic scanning Back to bricks. + Magnetic spectrometer. Ran from 2008 - 2012 3 observed events in the τ è h, τ è 3h and è µ channels τ This corresponds to 3.2 σ significance of non- null observation (3.5 σ significance with a likelihood approach) Signal (also reported on nue search) 09/12/13 Chris Walter - TAUP 2013 18 Noνa – Low Z calorimeter • 14 kton “totally acGve” liquid scinGllator detector Low Z tracking calorimeter: tracking + allow ?me for photons to convert and showers to develop. Low Z calorimeter (near and far detectors) No B field. Nova is unique in current generaon of experiments for addressing mass hierarchy using neutrino and an-neutrino beams. νeCC BG NC 09/12/13 Chris Walter - TAUP 2013 19 Uses an upgraded version of the current NuMi beam The NuMi beam will be upgraded from 300 -> 700 kw. One of the largest devices ever constructed from plasGc. There has been an impressive amount of R&D. Beam turned on last week! 09/12/13 Chris Walter - TAUP 2013 20 Detector Status CosmicRays! • Far detector completed ~May 2014 • First half near detector ready early 2014 09/12/13 Chris Walter - TAUP 2013 21 NOA CPV determination, 3+3 yr Expected Nova sin22 =0.095, sin22 =1.00 13 23 2.5 ) 2 m <0 SensiGvity 2 m2>0 1.5 1 0.5 significance of CP violation ( violation CP of significance 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / NOA hierarchy resolution, 3+3 yr sin22 =0.095, sin22 =1.00 ) 13 23 3.5 2 3 m <0 m2>0 2.5 2 1.5 1 0.5 significance of hierarchy resolution ( 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / 09/12/13 Chris Walter - TAUP 2013 22 Expected T2K Allowed Regions “Lucky! (δCP=-90)” 100% ν (true NH) 50% ν/50% anG-ν (true NH) 100% ν (true NH) 50% ν/50% anG-ν (true NH) w/ Reactor constraint w/ Reactor constraint 09/12/13 Chris Walter - TAUP 2013 23 Expected T2K Allowed Regions “Unlucky! (δCP=0)” 100% ν (true NH) 50% ν/50% anG-ν (true NH) 100% ν (true NH) 50% ν/50% anG-ν (true NH) w/ Reactor constraint w/ Reactor constraint 09/12/13 Chris Walter - TAUP 2013 24 MH using T2K and Nova NOA hierarchy resolution, 3+3 yr NOA hierarchy resolution, 3+3 yr 2 2 sin22 =0.095, sin22 =1.00 21 sin 2 =0.095, sin 2 =1.00 ) 13 23 + T2K at 5.5×10 POT ) 13 23 3.5 3.5 2 2 3 m <0 3 m <0 2 m2>0 m >0 2.5 2.5 2 2 1.5 1.5 1 1 0.5 0.5 significance of hierarchy resolution ( 0 significance of hierarchy resolution ( 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / / NOA hierarchy resolution, 3+3 yr NOA hierarchy resolution, 3+3 yr 2 2 2 2 21 sin 213=0.095, sin 223=1.00 sin 213=0.095, sin 223=1.00 + T2K at 5.5×10 POT 1 1 0.9 0.9 0.8 0.8 m2<0 m2<0 0.7 0.7 m2>0 m2>0 0.6 0.6 0.5 0.5 0.4 0.4 Fraction of Fraction of 0.3 0.3 0.2 0.2 0.1 Nova only 0.1 Nova + T2K 0 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 Significance of hierarchy resolution () Significance of hierarchy resolution () 09/12/13 Chris Walter - TAUP 2013 25 CPV using T2K and Nova NOA CPV determination, 3+3 yr 2 2 sin 213=0.095, sin 223=1.00 T2K only 50% ν/50% anG-ν 2.5 ) 2 m <0 Nova Only 2 2 STAT ONLY m >0 1.5 1 0.5 significance of CP violation ( violation CP of significance 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / NOA CPV determination, 3+3 yr 2 2 21 2012 systematics sin 213=0.095, sin 223=1.00 + T2K at 5.5×10 POT 2.5 ) 2 m <0 2 m2>0 1.5 1 0.5 significance of CP violation ( violation CP of significance Nova + T2K 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / 09/12/13 Chris Walter - TAUP 2013 26 Accelerator Neutrino Physics II: Long-term vision 09/12/13 Chris Walter - TAUP 2013 27 Our Strategy Since we have measured θ13 we need to (with high accuracy): – Measure the phase of δ and hopefully observe CP violaon – Determine the mass hierarchy [if not already done] – Make precision measurements of the mixing angles.